JP3204802B2 - Thermal recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material having high sensitivity and excellent storage stability.

[0002]

2. Description of the Related Art Recording materials using an electron-donating dye precursor (hereinafter, referred to as a color former) and an electron-accepting compound (hereinafter, referred to as a developer) include pressure-sensitive recording paper, heat-sensitive recording paper, and photosensitive pressure-sensitive recording paper. It is well known as a recording paper or a current-carrying thermosensitive recording paper. For example, British Patent 2,140,449, US Patent 4480052
No. 4436920, Japanese Patent Publication No. 60-23922,
JP-A-57-179636 and JP-A-60-123556
And No. 60-123557. In recent years, as the use of heat-sensitive recording paper has expanded, the demand for performance has also become widespread, and white powder is generated and adheres to the heat-sensitive recording surface, especially during long-term storage or high-temperature storage. Is strongly required.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a heat-sensitive recording material having high sensitivity and excellent storage stability.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermosensitive recording material having at least a color former, a developer for developing the color former and a thermosensitive color layer containing β-naphthylbenzyl ether. In the following general formula (I)
The surfactant represented by the formula (1) is added to the total solid content of the thermosensitive coloring layer in an amount of 1 %.
It was achieved by the heat-sensitive recording material which comprises adding to 5 wt%. General formula (I)

[0005] _{R-O- (CH 2 CH 2} O) n - SO 3 - M +

In the formula, R represents an alkyl group or an aryl group;
Represents an integer of 1 to 30, and M ⁺ represents an alkali metal ion or an ammonium ion .

The amount of the compound of the formula (I) used in the present invention is 1% by weight to 5% by weight based on the total solid content of the thermosensitive coloring layer. When added in an amount of 5% by weight or more, adverse effects such as deterioration of background fog appear. Further, n of the compound of the general formula (I) in the present invention has a large effect of suppressing dusting when the average value of n is 8 or more, and is more preferably used.

The alkyl group or aryl group represented by R may further have a substituent. The substituent of the alkyl group may have an aryl group, an alkylaryl group, or an alkenylaryl group, and the substituent of the aryl group may have an alkyl group, an alkenyl group, an arylalkyl group, or an arylalkenyl group.

Specific examples of the compound represented by formula (I) include polyoxyethylene lauryl ether sulfate sodium salt (average n ≒ 2, average n ≒ 3, average n ≒ 4) polyoxyethylene oleyl ether sulfate sodium salt (Average n ≒ 6, average n ≒ 19) polyoxyethylene nonylphenyl ether sulfate sodium salt (average n ≒ 4, average n ≒ 9) polyoxyethylene distyrylphenyl ether sulfate ammonium salt (average n ≒ 13) Can be

In the present invention, the color former, the developer, and the heat-fusible substance are dispersed in a water-soluble binder. The binder used in the present invention is 5% by weight based on 25 ° C. water. Compounds that dissolve as described above are preferable, and specific examples thereof include polyvinyl alcohol, methylcellulose, carboxymethylcellulose, starches (including modified starch), gelatin, gum arabic, casein, and styrene-
Examples thereof include a maleic anhydride copolymer hydrolyzate, carboxy-modified polyvinyl alcohol, polyacrylamide, and a saponified vinyl acetate-polyacrylic acid copolymer. These binders are used not only at the time of dispersion but also for the purpose of improving the strength of the coating film. For this purpose, styrene-butadiene copolymer, vinyl acetate copolymer, acrylonitrile-butadiene copolymer, acrylic Methyl acid
Latex binders of synthetic polymers such as butadiene copolymers and polyvinylidene chloride can also be used in combination. Alternatively, the same binder can be used for the undercoat layer.

The color former used in the present invention includes triarylmethane compounds, diphenylmethane compounds, xanthene compounds, thiazine compounds, spiropyran compounds and the like. A concrete example is disclosed in
-227253 and the like. If some of these compounds are disclosed, examples of triarylmethane compounds include 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide and 3,3-bis (p-dimethylaminophenyl) phthalide , 3- (p-
Dimethylaminophenyl) -3- (1,3 dimethylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, etc. Examples of the compound include 4,4'-bis-dimethylaminobenzhydrin benzyl ether, N-halophenyl-leuco auramine, N-2,4,5-trichlorophenyl leuco auramine and the like. Rhodamine-B-anilinolactam, rhodamine- (p-nitrino) lactam, 2- (dibenzylamino) fluoran, 2-anilino-3-methyl-6-diethylaminofluoran, 2-anilino-3-methyl-6 Dibutylaminofluoran, 2-anilino-3-methyl-6-N-
Ethyl-N-isoamylaminofluoran, 2-anilino-3-methyl-6-N-methyl-N-cyclohexylaminofluoran, 2-anilino-3-chloro-6-diethylaminofluoran, 2-anilino-3- Methyl-
6-N-ethyl-N-isobutylaminofluoran, 2
-Anilino-6-dibutylaminofluoran, 2-anilino-3-methyl-6-N-methyl-N-tetrahydrofurfurylaminofluoran, 2-anilino-3-methyl-6-piperidinoaminofluoran, 2- (o-chloroanilino) -6-diethylaminofluoran, 2-
(3,4-dichloroanilino) -6-diethylaminofluoran, etc., thiazine compounds include benzoyl leucon methylene blue, p-nitrobenzyl leucomethylene blue and the like, and spiro compounds include 3-methyl-spiro- Dinaphthopyran, 3-ethyl-spiro-dinaphthopyran 3,3'-dichloro-spiro-dinaphthopyran, 3-benzylspiro-dinaphthopyran,
3-Methyl-naphtho- (3-methoxy-benzo) -spiropyran, 3-propyl-spiro-dibenzopyran and the like.

As the color developer used in the present invention, a phenolic compound or a salicylic acid derivative and a polyvalent metal salt thereof are preferable. To illustrate some of these, phenolic compounds include 2,2'-bis (4-hydroxyphenyl) propane, 4-t-butylphenol, 4-phenylphenol, 4-hydroxydiphenoxide,
1'-bis (3-chloro-4-hydroxyphenyl) cyclohexane, 1,1'-bis (4-hydroxyphenyl) cyclohexane, 1,1'-bis (3-chloro-4
-Hydroxyphenyl) -2-ethylbutane, 4,4 '
-Sec-isooctylidene diphenol, 4,4'-se
c-butylidene diphenol, 4-tert-octylphenol, 4-p-methylphenylphenol, 4,4 '
-Methylcyclohexylidenephenol, 4,4'-isopentylidenephenol, benzyl p-hydroxybenzoate and the like.

The salicylic acid derivatives include 4-pentadecyl salicylic acid, 3,5-di (α-methylbenzyl) salicylic acid, 3,5-di (tert-octyl) salicylic acid,
-Octadecylsalicylic acid, 5-α- (p-α-methylbenzylphenyl) ethylsalicylic acid, 3-α-methylbenzyl-5-tert-octylsalicylic acid, 5-tetradecylsalicylic acid, 4-hexyloxysalicylic acid,
-Cyclohexyloxysalicylic acid, 4-decyloxysalicylic acid, 4-dodecyloxysalicylic acid, 4-pentadecyloxysalicylic acid, 4-octadecyloxysalicylic acid, and the like, and zinc, aluminum, calcium, copper, and lead salts thereof. When a water-soluble compound is used, the effect of suppressing background fog is remarkable.

These developers are preferably used in an amount of 50 to 800% by weight of the color former, more preferably 10 to 800% by weight.
0 to 500% by weight. If the content is less than 50% by weight, the coloring is not sufficient, and if it is added more than 800% by weight, no further effect can be expected, which is not preferable.

In the heat-sensitive recording material of the present invention, a sensitizer can be contained in the heat-sensitive coloring layer in order to improve the thermal response. Preferred examples include benzyl p-benzyloxybenzoate, β-naphthyl-benzyl ether, stearamide, stearyl urea, p-benzylbiphenyl, di (2-methylphenoxy) ethane, di (2-methoxyphenoxy) ethane, β-naphthol (p-methylbenzyl) ether, α-naphthylbenzyl-ter,
1,4-butanediol-p-methylphenyl ether, 1,4-butanediol-p-isopropylphenyl ether, 1,4-butanediol-p-tert-octylphenyl ether, 1-phenoxy-2- (4- Ethylphenoxy) ethane, 1-phenoxy-2- (4-
Chlorophenoxy) ethane, 1,4-butanediol phenyl ether, diethylene glycol-bis (4-methoxyphenyl) ether, and the like. Among these, in the present invention, when β-naphthyl-benzyl ether is used as a sensitizer, a thermosensitive recording material having the highest sensitivity and excellent storage stability can be obtained.

The above-mentioned sensitizers are used alone or as a mixture. In order to obtain a sufficient thermal response, it is preferably used in an amount of 10 to 200% by weight, more preferably 20 to 150% by weight, based on the electron-accepting compound. % By weight.

As the pigment, calcium carbonate, barium sulfate, lithopone, wax, kaolin, silica, amorphous silica, aluminum hydroxide and the like are used.

If necessary, metal soap, wax, surfactants other than those used in the present invention, antistatic agents, ultraviolet absorbers, defoamers, conductive agents, fluorescent dyes, etc. may be added.

As the metal soap, higher fatty acid metal salts are used, and zinc stearate, calcium stearate,
Aluminum stearate or the like is used. As the wax, a paraffin wax, a microcrystalline wax, a carnauba wax, a methylol stearamide, a polyethylene wax, a polystyrene wax, a fatty acid amide wax or the like is used alone or in combination.

As the surfactant, a sulfosuccinic acid-based alkali metal salt and a fluorine-containing surfactant are used.

It is preferable to add a decoloring inhibitor to the heat-sensitive coloring layer in order to prevent decoloring of the image printed portion and to make the formed image fast. A phenol compound, particularly a hindered phenol compound, is effective as the decoloration inhibitor. For example, 1,1,3-tris (2-methyl-4-hydroxy-tert-butylphenyl) butane, 1,1,3
-Tris (2-ethyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (3,5-
Di-tert-butyl-4-hydroxyphenyl) butane;
1,1,3-tris (2-methyl-4-hydroxy-5
-Tert-butylphenyl) propane, 2,2'-methylene-bis- (6-tert-butyl-4-methylphenol), 2,2'-methylene-bis (6-tert-butyl-
4-ethylphenol), 4,4'-butylidene-bis- (6-tert-butyl-3-methylphenol), 4,
4'-thio-bis (3-methyl-6-tert-butylphenol), and the like. The use amount of such a phenolic compound is preferably 1 to 200% by weight, more preferably 5 to 50% by weight, based on the developer.
It is.

These materials are mixed and then applied to a support.

As the support, paper, synthetic paper, various bases and the like are used, and it is preferable to provide an undercoat layer on the support in advance to obtain high smoothness. The applied heat-sensitive recording material is dried, subjected to a treatment such as a calender, and provided for use.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples.

[0025]

【Example】

Example 1 (Preparation of undercoat paper) 80 g of calcined kaolin (manufactured by Engelhardt; Ansilex 93) was dispersed with a homogenizer together with 160 g of a 0.5% aqueous solution of sodium hexametaphosphate to obtain a pigment dispersion. 16 g of styrene-butadiene latex (manufactured by Sumitomo Nogatax; SN307, solid content concentration: 48%) and 10% of polyvinyl alcohol (manufactured by Kuraray; PVA-117) were added to the pigment dispersion.
An aqueous solution for undercoat layer was obtained by adding 24 g of an aqueous solution. To prepare a coated and dried undercoat paper so that 8 g / m ² of the undercoat coating liquid for high quality paper of 50 g / m ^2.

(Preparation and coating of coating solution for thermosensitive coloring layer) 20 g of 3-dibutylamino-6-methyl-7-anilinofluoran was added to polyvinyl alcohol (manufactured by Kuraray Co., Ltd .;
PVA-105) 24-4 with 100 g of 5% aqueous solution
The mixture was dispersed in a ball mill for 8 hours to obtain a dispersion having an average particle size of 1.0 μm. Further, 40 g of bisphenol-A and 40 g of β-naphthylbenzyl ether were dispersed in a ball mill for 24 to 48 hours together with 400 g of a 10% aqueous solution of polyvinyl alcohol (manufactured by Kuraray Co., Ltd .; PVA-105) to obtain an average particle size of 1.
A 0 μm dispersion was obtained. In addition, 80 g of calcium carbonate (manufactured by Shiraishi Industry Co., Ltd .; Homocal D) was dispersed with a homogenizer together with 160 g of a 0.5% aqueous solution of sodium hexametaphosphate to obtain a pigment dispersion.

The dispersion obtained as described above was mixed, and 50 g of a 21% zinc stearate emulsion and 12 g of a 20% aqueous solution of polyoxyethylene distyryl phenyl ether sulfate ammonium salt (average n ≒ 13) were added.
Was added to obtain a coating solution for thermal paper. The heat-sensitive recording material of the present invention was obtained by applying the composition on a wire bar so as to have a dry coating amount of 7 g / m ² on the undercoated paper and drying in an oven at 50 ° C.

[0028]

[0029]

REFERENCE EXAMPLE 1 In Example 1, an aqueous solution of distyryl phenyl ether sulfate ammonium salt (average n を 1.3) was used.
A thermosensitive recording material was obtained in the same manner as in Example 1 except that 0 g was added to the undercoat layer coating solution instead of the thermosensitive coloring layer coating solution.

Example 2 In Example 1, 12 g of an aqueous solution (20%) of an aqueous solution of sodium polyoxyethylene nonylphenyl ether sulfate (average n ≒ 9) was used instead of ammonium polyoxyethylene distyrylphenyl ether sulfate.
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that it was added.

Example 3 In Example 2 , an aqueous solution of sodium salt of polyoxyethylene nonylphenyl ether sulfate (average n ≒)
9) Example 2 except that the addition amount of (20%) was changed to 60 g.
A heat-sensitive recording material was obtained in the same manner as described above.

Reference Example 2 The procedure of Example 1 was repeated, except that 40 g of P-benzylbiphenyl was used instead of β-naphthylbenzyl ether, and 2.4 g of ammonium polyoxyethylene distyrylphenyl ether sulfate was used. Thus, a heat-sensitive recording material was obtained.

[0034] In Comparative Example 1 Example 1, except for using sulfosuccinic acid di-4-methylpentyl ester sodium salt aqueous solution (20%) in place of the polyoxyethylene distyryl phenyl ether sulfate ammonium salt as in Example 1 To obtain a heat-sensitive recording material.

Comparative Example 2 A heat-sensitive recording material was obtained in the same manner as in Example 1, except that the amount of the aqueous solution of polyoxyethylene distyrylphenyl ether sulfate ammonium salt was changed to 0.1 g.

Comparative Example 3 A heat-sensitive recording material was obtained in the same manner as in Example 1, except that ammonium polyoxyethylene distyrylphenyl ether sulfate was not added.

Comparative Example 4 In Example 1, the polyoxyethylene distyryl phenyl ether sulfate ammonium salt (average n ≒)
A heat-sensitive recording material was obtained in the same manner as in Example 1 except that the addition amount of 3) was changed to 120 g.

(Preparation and Evaluation of Storage Stability Evaluation Sample)
The heat-sensitive recording paper thus obtained was heated at 50 ° C. for 3 days, left at room temperature for 1 day, the recording surface was rubbed with a black cloth, and the amount of powder adhering to the cloth was visually evaluated. . After heating in an oven at 60 ° C. for 24 hours, the background fog density was measured with a Macbeth reflection densitometer RD-918.

(Evaluation of Sensitivity) The sensitivity was measured by subjecting the obtained heat-sensitive recording paper to a surface treatment with a low-pressure calender, and using Kyocera Corporation.
Using a thermal head (KLT-216-8MPD1) and a thermal printing test apparatus having a pressure roll of 100 kg / cm ² immediately before the head, the pulse width was set to 0 using a pressure roll under the conditions of a head voltage of 24 V and a pulse cycle of 10 ms. The printing was performed at 0.8 ms, and the printing density was measured with a Macbeth reflection densitometer RD-918. The above evaluation results are shown in Table 1.

[0040]

[Table 1]

As can be seen from Table 1, according to the present invention, a heat-sensitive recording material having high sensitivity and excellent storage stability was obtained.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-299384 (JP, A) JP-A-57-193387 (JP, A) JP-A-1-209188 (JP, A) JP-A-4- 135786 (JP, A) JP-A-5-318925 (JP, A) JP-A-58-166096 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5 / 28-5 / 34

Claims (1)

(57) [Claims] 1. A thermosensitive recording material having at least a color former, a developer for developing the color former, and a thermosensitive color layer containing β-naphthylbenzyl ether, wherein the thermosensitive color layer has the following general formula (I): Heat-sensitive surfactants shown
A heat-sensitive recording material comprising 1 to 5% by weight based on the total solid content of the color layer . General formula (I) R-O- (CH 2 CH 2 O) n - SO 3 - M + wherein R is an alkyl group, an aryl group, n represents an integer of 1 to 30, M ⁺ is an alkali metal ion or Ammonium ion
Shows the emissions.